The effects of distilled water on heteromorphosis in a tubularian hydroid, T. crocea

Conclusions

1)

If distal pieces ofT. crocea are allowed to regenerate in sea-water whose concentration is reduced by adding distilled water until it is 50–70% of the concentration of the normal sea-water, a larger percentage of them will produce heteromorphic hydranths than if they are allowed to regenerate in normal sea-water.

2)

The maximum number of heteromorphic hydranths produced occurs in sea-water diluted to about 55% of the normal sea-water.

3)

Isosmotic solution of cane-sugar is poisonous to these animals and therefore cannot be used to determine whether decrease of osmotic pressure is the cause of the increase of the production of heteromorphic hydranths or not.